In filling machines for liquid food packages, such as e.g. sold by Tetra Pak under the name Tetra Pak A1, a web of packaging material is sterilized, and is subsequently formed into a tube by making the longitudinal edges of the web overlap each other and sealing the overlap area. This tube is filled with liquid food continually, and the tube of packaging material is transversally sealed and cut such that separate packages with liquid food are formed.
The transversally seal procedure is typically carried out by a sealing jaw arrangement. The sealing jaw arrangement often comprises a pressure jaw assembly and a heating jaw assembly, wherein the portion of the tube subject to receive a transversal seal is arranged in between the pressure jaw assembly and heating jaw assembly during the formation of the seal. The pressure jaw assembly is arranged to provide means for allowing the sealing jaw arrangement to press the packaging material of the tube during the formation of the seal, and the heating jaw assembly is arranged to provide sufficient heat to the packaging material of the tube needed for the formation of the seal.
In order for the pressure jaw assembly to provide means enabling a sufficient applied pressure to the tube, the pressure jaw assembly often comprises some type of compressing means and a guiding arrangement adapted for internally guiding parts of the pressure jaw assembly. One such guiding arrangement comprises rubber bushings.
However, the pressure jaw assembly of the sealing jaw arrangement may give rise to an uneven sealing pressure due to e.g. fatigue of the rubber bushings. Thus, there is a need in the industry for an improved pressure jaw assembly.